g_in_k_o said the following on 12/31/2007 3:23 PM:

snip

You can bubble your own CO2 with yeast, sugar and water in a 2 liter soda
bottle. It's a pain to keep feeding the yeast, but it's pretty cheap and
does a good job for many plants. Google "DIY CO2" should get some info to you.

URL: http://thereeftank.com/forums/showthread.php?t=90039&page=23

About half way down that page is a section where the guy posted pictures
and instructions on how to make a DIY CO2 generator. I found that
article while researching for a reef tank. I made one two nights ago and
it works good. Too good in fact. I double dosed the yeast trying to jump
start my plant tank and ran into a problem worse than recharging the
yeast. Trying to regulate the CO2. Instead of bending a stiff piece of
tubing, I simply used flex tubing and ran it through the bottom of the
strainer (after drilling a hole for it). The problem is that it produces
so much CO2 that the bubbles actually build up and cause my filter to
"dry run" for about a half a second every minute or so. I am going to
have to put a T in it and split it up. Impossible to regulate.

--
Randy
Chance Favors The Prepared Mind